Manufacture of earthenware.



' UNITED STATES PATENT OFFICE.

EDWARD GOODRICH AOHESON, OF NIAGARA FALLS,.CANADA, ASSIGNOR TO THEACHESON COMPANY, OF NIAGARA FALLS, NEW YORK, A COR- PORATION OF NEWJERSEY.

MANUFACTURE OF EARTH ENWARE.

SPECIFICATION forming part of Letters Patent N 0. 722,791, dated. March17, 1903 Application filed December 18, 1901. Serial No. 86,466. (Nospecimens.)

ing strength of the clays, silicious com pounds,

and earthy minerals.

It is well known that while the use of articles of pottery orearthenware is in many instances most desirable the material cannot beemployed in some cases, first, because of its lack of strength, and,secondly, because of the shrinkage and warping of the material duringmanufacture, rendering it difficult to insure the production of articlesof uniform shape and dimensions.

I have discovered that it is practicable to so treat clay and otherearthy materials as to insure greater strength in the products madetherefrom, to greatly reduce shrinkage and warping in the process ofdrying and baking, and also so as to very materially increase solubilityand the plasticity of the material. This I find may be accomplished bythe addition to the material of what I term a modifying agent. Difierentagents may be employed; but I have discovered that earthy materials whennon-plastic may be rendered plastic and plastic ones made more plasticby treatment with an agent having the astringent tannic principlescontained in nutgalls, tea-leaves, sumac, hemlock-bark,oak-bark,cutch,and many other barks,leaves, nuts, and woods, all ofwhich contain tannin or are capable of those reactions that arerecognized as or considered due to tannin.

The Word tannin as I herein use it is not confined to gallotannic acidor any one of the many compounds known to chemistry as tannic acids, butto the entire class. Wattss Dictionary of Chemistry says on thissubject, under the caption Tannin, Tannic Acidsz Under the above namesare included a large series of compounds occurring in the vegetablekingdom of difierent constitutions, many of which have been veryimperfectly studied. Therefore while I confine the words modifying agentto agents of a vegetable origin I would define them in their applicationto this descriptive matter as being broader and more general even thanthat above attributed to the word tannin, and I include any compoundderived from vegetable matter containing the active principle necessaryfor the production of the changes or modifications or transformationsherein specified as occurring in the clay. Thus an aqueous infusion ofcommon straw will produce increased softness, thinness, or fluidity ofclay.

In carrying out my invention I make a body composition by subjecting theclay, silicious compound, or earthy mineral to a more or less prolongedtreatment in or with a solution of tannin or equivalent modifying agent.Thus when I wish to improve the plastic and binding qualities of kaolinI place a weighed amount of the earthy material, as clay, in somesuitable tank or vat, add the desired amount of tannin, and thenthoroughly wet the mass with water, or I may dissolve the tannin or itsequivalent and add the solution to the clay. The whole is thenthoroughly stirred and allowed to stand until the desired action hasoccurred. Other things being equal, the degree of action and efiect on agiven clay is measured by the amount and activity of the added materialand the duration of exposure. I have had good results with kaolin towhich was added one-half of one per cent. of gallotannic acid, withsufficient water to wetand cover the mass and allowing the same to standfor twenty-four hours. Much better results were obtained with kaolin towhich was added two per cent. of catechu and enough water to wet andcover the mass,

allowing the whole to stand for one month,

and the effect was still further increased when the mass stood underwater for two months. I have found that clay treated in this way ischanged in a most remarkable manner. Thus the amount of water requiredto reduce it to a given. degree of softness, thinness, or fluidity maybe decreased over fourteen percent. The plasticity of the clay is muchincreased, it being easier to work or form into delicate shapes. Theshrinkage in drying is much reduced, while the tensile strength of thedried and baked clay may be increased over forty per cent.

The presence of tannin or other modifying agent produces a chemical orphysical change in the clay or earthen material that is not dependentupon its continued presence, as I have found that after the treatmenthas been prolonged sufficiently to produce a desired efiect the clay maybe thoroughly washed and all trace of soluble tannin removed withoutdestroying the peculiar characteristics that have been imparted to it bythe previous treatment. It will therefore be seen that I have produced anovel article of earthenware having much greater strength thanearthenware articles heretofore made and that I have provided a bodycomposition which is not only of much greater plasticity, but which willwhen formed into desired shapes and dried or baked retain its form andproportions to a greater degree than ordinary body compositions. It willfurther be seen that I have discovered that it is possible to producethe desired efiects by the use of a modifying material combined with theearthen material and that a modifying material containing tannin ispeculiarly effective.

I am aware that salts of the alkalies and other substances have beencombined with clay to act as a flux in burning; but my invention isdistinguished from this by the discovery that the agents specified abovewill act to modify the character of the body whetherburned ornot,producingeifects never before known as resulting from such use.

Without limiting myself to the use of the specific materials orproportions stated, I claim 1. The new manufacture of earthenware,substantially as hereinbefore described, resulting from treating a bodymaterial with a modifying agent having effects like those due to theeffects of tannin thereon, possessing the characteristics of increasedstrength and plasticity and decreased absorption of water and shrinkagein drying.

2. A new manufacture of earthenware, comprising a body material treatedwith tannin as a modifying agent, substantially as described.

3. The within-described improvement in the manufacture of earthenware,which consists in treating a body material with a modi fying agenthaving the effects on the body material like those due to the effects oftannin on said material, then forming the mass into the desired shape.

In testimony whereof I have signed my name to this specification in thepresence of two subscribiu g Witnesses.

ED WARD GOODRICH ACHESON.

Witnesses:

FRANCIS A. J Frrz GERALD, FRANK N. Con.

